The FAA Advisory Circular (Ac No. 25.795-2A) specifies that protection of a passenger aircraft flight deck requires the flight deck door to be able to resist forcible intrusion by a 300 J (221.3 ft-pounds) localized loading event, and sustain a 1113 N (250 lb) tensile load applied to accessible hand holds (e.g. a door knob or handle). It also requires a capability to resist multiple hits from small arms fire. The Advisory indicates that a flight deck door must also be able to resist small arms fire. In particular, it specifies that the door must:                Resist penetration by a 9 mm full metal jacketed round nose bullet with mass of 8 g and reference velocity of 436 m/s (FMJ RN round).        Resist penetration by a .44 Magnum (JHP) jacketed hollow point bullet with a nominal mass of 15.6 g and impact velocity of 436 m/s.        Survive four impacts at zero obliquity and 2 impacts at a 30° obliquity by each projectile (12 impacts).        Have an aerial density of substantially less than 1 lb/ft2 (4.9 kg/m2).        